For Hero coins, u must have score of 600 points - u need 20 rounds with any of the following :
- Abyss of Arcadia
- Nightmare of Arcadia
- Revenge of Arcadia
- Shadow of Arcadia
- Curse of Arcadia
All mobs r from Tairan and Alber, and u need 500 coins to open a single box.
Good Luck

The most painful goodbyes are the ones that are never said and never explained.